Pesticides are chemicals designed to cause biologic harm to plants, insects, and other pests. Widespread use in agriculture and in urban areas creates an opportunity for exposure to a large segment of the population. Epidemiologic investigations are undertaken to identify and clarify cancer risks from pesticide exposure. The Agricultural Health Study is a major effort which is designed to evaluate the relationship between pesticides and other agricultural factors and the risk of cancer and other diseases. Enrollment in this study includes about 90,000 men and women from Iowa and North Carolina. From 1993-1997 detailed information was obtained by self-administered questionnaire and in the next three years this information is being updated and expanded by telephone interview. Telephone interviews include questions on pesticides used and other agricultural exposures, lifestyle factors, medical and family history of disease, and diet. We are also attempting to collect buccal cell samples as a source of genomic DNA on all members of the cohort. Analyses on cancer incidence and other chronic diseases is just getting underway. The risk of visits to health care providers resulting from pesticide exposure was higher among commercial applicators than farmers, among men than women, and among North Carolina applicators than Iowa applicators. Frequency of health care visits was associated with frequency of pesticide application. Several other projects to evaluate the cancer risk from pesticide exposure are underway. During the past year, analysis of data from case-control studies of non- Hodgkins lymphoma noted an association with agricultural use of lindane, but not with DDT. Farmers were found to be at elevated risk for prostate cancer in a study of mortality in 24 states. Contrary to earlier investigations, however, the risk of breast cancer was not associated with serum levels of DDT among women in Mexico City. A methodologic study to compare pesticide levels in dust samples from vacuum cleaner bags with levels from a high-volume surface sampler (HVSS) found a high degree of correlation. This suggests that collection of vacuum cleaner bags, which is a simpler and less expense approach than the HVSS, provides a reliable indication of pesticide levels on dust in homes. Several feasibility studies have been conducted among migrant and seasonal farm workers to determine appropriate methods for epidemiologic investigations in this understudied group. Results from this effort will appear in a special volume of the American Journal of Industrial Medicine in the near future. A review of the literature was conducted which suggested that pesticides may play a role in the development of childhood and adult cancers. Recently completed case-control studies of cancers of the brain and stomach in Nebraska will provide the opportunity to assess the role of agricultural, general environmental, and lifestyle factors in the development of these tumors. Blood and urine have been collected from 30 applicators applying the herbicide 2,4-D to relate dose to possible biologic effects including DNA mutations, chromosome aberrations, and immune system alterations. - Human Subjects & Human Tissues, Fluids, Cells, etc.